This invention relates to a coating layer drying system for a cathode ray tube (CRT), and more particularly to the drying system in which it is possible to dry a coating layer at a low temperature using a super critical drying method.
In general, a CRT includes a panel inside of which a black matrix layer and a fluorescent layer are formed, a funnel which is internally attached to the panel and on the circumference of which a deflection yoke is installed, and a bulb which is formed with a neck equipped with an electron gun, the neck being connected to the rear of the funnel.
When manufacturing the CRT like the above, a coating layer is formed on the outer surface of the panel, The coating layer prevents static electricity generated by an electrostatic charge and increases the contrast of the pictures realized in the CRT.
The usual method used in forming the coating layer involves the following processes: a process for injecting a little coating fluid into the center of the outer surface of the panel placed in the bulb; a process for turning the bulb around in order that the coating fluid may be applied over the complete surface of the panel; a process for moving the bulb retaining the coating layer into a drying system; and a process for drying the coating layer.
In general, the drying system is furnished with a furnace which keeps its inner temperature at a stable and constant level using an electric heater or hot wind. In order to dry the coating layer using the furnace, the following steps are needed: a step for elevating the inner temperature of the furnace to a certain degree; a step for moving the bulb retaining the coating layer inside the furnace; and a step for drying the coating layer by the heat in the inner part of the furnace.
However, the conventional drying system for the CRT has some problems. For example, the furnace used in the drying system is very large. Also, the drying system needs a complicated electric heater or a complicated device ventilating hot wind. As a result, the drying system bears a high installation fee and exorbitant maintenance costs.
Furthermore, there is another problem in the drying system. That is, when the coating layer is dried in the inside of the furnace, since the length of the furnace is substantial, total drying time becomes increased as the time required for the bulb to pass through the entire length of the furnace is great, and thus the drying system results in a drop in operation efficiency.